Wanted: A Base of Evidence

Cytocompatibility and Antibiofilm Activity of Calcium Hydroxide Mixed with Cyperus articulatus Essential Oil and Bio-C Temp Bioceramic Intracanal Medicament

Calcium hydroxide represents the most commonly used intracanal dressing between sessions; however, it may not be effective against all types of microorganisms. Several compounds of plant origin have attracted increasing attention from researchers in recent years. The objective of this study was to evaluate the cytocompatibility and antimicrobial activity of calcium hydroxide associated with the essential oil of Cyperus articulatus and the new bioceramic intracanal medicament Bio-C Temp®. Five experimental groups were designed: group Ca-C. articulatus essential oil; group CHPG-calcium hydroxide associated with propylene glycol; group CHCa-essential oil of C. articulatus associated with calcium hydroxide; and group U-UltraCal® XS; group BCT-Bio-C Temp®. The control group was a culture medium. Cytocompatibility was assessed by the methyltetrazolium (MTT) assay after exposure of the Saos-2 human osteoblast-like cell line to dilutions of commercial products/associations for 24 h and 72 h. The antimicrobial activity against mature Enterococcus faecalis biofilm was evaluated by the crystal violet assay. All commercial products/associations showed a cell viability similar to or even higher than the control group (p > 0.05) for both periods evaluated. C. articulatus essential oil associated or not with calcium hydroxide showed better antibiofilm capacity. C. articulatus associated or not with calcium hydroxide showed superior cytocompatibility and antimicrobial capacity, representing a promissory intracanal medicament.

Precision-milled simulated curved root canals in bovine dentine for the assessment of chemo-mechanical root canal preparation

AIM

The aim was to develop a standardized curved root canal model in bovine dentine and to assess whether that natural substrate would behave differently from the resin in standard plastic training blocks when prepared chemo-mechanically. The impact of substrate microhardness on simulated canal transportation was considered.

METHODOLOGY

High-precision computer numerical control (CNC) milling was used to recreate a simulated root canal from a resin training block (Endo Training Bloc J-Shape, size 15) in longitudinally sectioned, dis- and re-assembled bovine incisor roots. Optical overlays obtained from 10 resin blocks were used to identify an average canal and program the CNC milling apparatus accordingly. Resin and dentine microhardness were measured. Simulated root canals in resin training blocks and their bovine counterparts were then instrumented at 37°C using Reciproc R25 instruments (VDW) with water or 17% EDTA (n = 10). Open-access image processing software was used to superimpose and analyse pre- and postoperative images obtained with a digital microscope. Centering ratios were averaged to indicate canal transportation. The effects of substrate and irrigant on canal transportation were assessed by two-way anova.

RESULTS

Superimposed images showed that resin blocks under investigation varied considerably in terms of simulated canal length and curvature, whilst the milled canals were highly similar. The microhardness of dentine was more than three times higher than that of the resin. Conversely, canal transportation was considerably greater in dentine compared to resin, and in dentine had a tendency to be increased by EDTA. There was a strong effect of substrate on canal transportation (p < .001), no overall effect of irrigant, and a marginally significant interaction between irrigant and substrate (p = .077).

CONCLUSIONS

CNC milling allows to create standardized simulated curved root canals in bovine dentine. These models may be useful to test and compare materials and concepts of chemo-mechanical root canal instrumentation. Microhardness is a bulk feature that does not predict the response to chemo-mechanical instrumentation of a composite material such as dentine.

Methodologies used for testing the sealability of endodontic temporary fillings in vitro: A narrative review

Introduction

The ability of the temporary filling to seal endodontic access cavities may be crucial for the success of endodontic treatment. Numerous in vitro studies have investigated the sealability of the temporary fillings used in endodontic treatments. However, in vitro sealability studies have been criticized for their inconsistent results and questionable clinical relevance. Some journals have imposed moratoriums on publishing such studies to encourage researchers to test their validity and clinical relevance. Since the implementation of this moratorium, little progress has been made in this field. To further encourage researchers to investigate the reliability of these studies, this review presents an overview of the methodologies of studies that examine the ability of temporary filling materials to seal the endodontic access cavity in vitro and discusses the criticisms of these studies in detail.

Materials and Methods

PubMed, Scopus, and Embase electronic databases were searched to identify studies that tested in vitro the ability of temporary filling materials to seal endodontic access cavities. Only original articles published in English between 01/01/1970 and 28/02/2022 were included.

Results

The search yielded 551 results. After removing duplicates and excluding studies that did not meet the inclusion criteria, 94 studies were included in this review.

Conclusion

Although clinical studies may be the best way to test the performance of temporary fillings, the ethical importance of conducting preliminary in vitro studies is undeniable. It seems that questioning the reliability of in vitro sealability studies is not based on sufficient scientific evidence and that the inconsistencies in the results of these studies may be due to differences in the methodological and clinically relevant variables between them, rather than due to their unreliability.

Biological considerations of dental materials as orifice barriers for restoring root-filled teeth

There is ample published literature regarding the technical aspects of restoring root-filled teeth, but little concerning the biological impacts, consequences, and criteria for the selection of direct restorative materials following endodontic treatment. The provision of an effective coronal seal in addition to a sound root filling is known to be important in the prevention of root canal infection. This review seeks to explore the evidence concerning the selection of dental materials in the restoration of root-filled teeth, specifically with a close examination of the properties of commonly used materials as orifice barriers. © 2023 Australian Dental Association.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-computed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

In Vitro Evaluation of the Antibacterial Activity of EndoSeal MTA, iRoot SP, and AH Plus against Planktonic Bacteria

This study aimed to investigate the antibacterial activity of three endodontic sealers, AH Plus, iRoot SP, and EndoSeal MTA, against four planktonic bacteria species. The antibacterial activity of the three endodontic sealers was assessed using a modified direct contact test. Bacteria suspension of Actinomycoses viscosus, Enterococcus faecalis, Staphylococcus aureus, and Streptococcus mutans were left in contact with the sealers that were pre-set or set for 1, 3, 7, and l4 days for an hour. Freshly mixed AH Plus and EndoSeal MTA were highly effective against all four tested bacteria as no surviving bacteria were recovered after treatment. Meanwhile, freshly mixed iRoot SP was not able to kill all bacteria, regardless of the species, demonstrating a weak antibacterial effect. After 24 h, AH Plus lost its antibacterial activity. EndoSeal MTA showed a strong and extended bactericidal effect against S. aureus and S. mutans for 3 days and A. viscosus for 7 days. In conclusion, fresh AH Plus and EndoSeal MTA exhibited a potent effect against all four bacteria species. EndoSeal MTA remained effective after setting when tested against A. viscosus, S. aureus, and S. mutans. Among all tested sealers, iRoot SP demonstrates the weakest antibacterial activity.

A critical analysis of research methods and experimental models to study root canal fillings

Canal filling materials and techniques have been one of the most studied topics in Endodontics. A simple search using the mesh term "root canal filling" in PubMed revealed more than 11,000 articles, an impressive number that is much higher than "root canal disinfection" (5,544 articles) or even the popular "root canal preparation" (8,527 articles). The overriding importance attributed to root filling procedures is not merely intuitive. It derived from the appealing relevance given by the appearance of the white lines in common radiographs grounded on retrospective clinical data that had identified the quality of a root filling as one of the major causes of treatment failure (lack of healing). Since the publication of the Washington study, impressive efforts have been made for the release of new materials and techniques, as well as, for the development of a plethora of laboratory methods to assess the quality of root filling procedures. This narrative review aims to address and discuss the most relevant laboratory methods to assess the root canal filling. Since filling quality improvements have not translated into higher success rates, as reported in longitudinal clinical studies, more than to deliver a simple methodology-based review, this paper aims to present an in-depth critical view on the assessment of laboratory methods used to study the filling materials and techniques. Recent data indicate that the long-term dimensional stability/degradation over time of endodontic sealers plays a central role in the treatment outcome. In this context, laboratory methods should be developed focusing on predicting, at least to some degree, the long-term clinical behaviour of root canal fillings, rather than simply ranking different materials or techniques.

The presence of smear layer affects the antimicrobial action of root canal sealers

AIM

To assess the chemical and microstructural characteristics of dentine after the use of two irrigation protocols and correlate this with the antimicrobial properties of hydraulic calcium silicate cement (HCSC) sealers and changes to the dentine structure/chemistry after sealer placement.

METHODOLOGY

Two irrigation protocols - Protocol A using 2% NaOCl used 5 mL/5 min and Protocol B with 2% NaOCl (5 mL/5 min) followed by 17% EDTA (5 mL/3 min) - were used to prepare dentine. The chemical and microstructural changes following irrigation were assessed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy (n = 5) on dentine obtained from the mid-root and coronal parts of extracted human teeth. Four sealers (AH Plus, BioRoot, MTA Fillapex, TotalFill) were characterized by SEM/EDS (n = 3). The ability of the sealers to eradicate intratubular Enterococcus faecalis biofilms was assessed by live/dead dye and confocal laser scanning microscopy to measure the percentage of living cells. The effect of combined irrigation and root filling on dentine was assessed by SEM and EDS analysis (n = 5). Statistical analysis was undertaken using one-way anova and a number of post hoc tests to detect intergroup differences. The F-test was used for comparison of variances in the microbiology testing.

RESULTS

The use of NaOCl alone left the smear layer intact, with traces of chlorine remaining on dentine. The use of BioRoot sealer restored the calcium levels of dentine which had been depleted by the irrigation with EDTA. BioRoot exhibited antimicrobial properties against intratubular bacteria even in the presence of smear layer (Protocol A). Smear layer removal improved the bactericidal effect of all sealers and Ca²⁺ leaching. The use of a chelating agent was important for the intratubular sealer penetration for AH Plus but not the other sealers.

CONCLUSION

The removal of smear layer was necessary for penetration of AH Plus into the dentinal tubules. BioRoot was a more effective sealer in reducing the bacterial load in the dentinal tubules than the other materials tested and the presence of smear layer did not affect its activity.

Effects of Ultrasonic Activation on Root Canal Filling Quality of Single-Cone Obturation with Calcium Silicate-Based Sealer

Background: We evaluated the effects of ultrasonic activation on root canal filling quality of the single-cone (SC) obturation technique with calcium silicate sealers and gutta percha cones. Methods: Thirty-six human single-rooted premolars were obturated with gutta percha and sealer. For the continuous wave (CW) group (n = 12), AH Plus with a continuous wave technique was used. The SC group (n = 12) received EndoSequence BC sealer with a single-cone technique. The SCU (SC with the addition of ultrasonic activation) group (n = 12) received the same treatment. Micro-computed tomography was used to scan the teeth, and the void volume within the root canal was evaluated at the apical, middle, and coronal levels. Then cross-sections were observed under a light microscope and scanning electron microscope (SEM). Results: Void volume was significantly lower in the SCU group than in the CW and SC groups. There were no statistically significant differences between the CW and SC groups. The SCU group had fewer voids than the CW and SC groups in the coronal and middle third areas. Specimens showed no apparent gaps or voids in any group. SEM images revealed both gap-free and gap-containing regions at different levels in all groups. Conclusions: Single-cone obturation with calcium silicate-based sealers might obtain enhanced filling quality when used with ultrasonic activation.

The Antibacterial Effects of Resin-Based Dental Sealants: A Systematic Review of In Vitro Studies

This review aimed to assess the antimicrobial effects of different antibacterial agents/compounds incorporated in resin-based dental sealants. Four databases (PubMed, MEDLINE, Web of Science and Scopus) were searched. From the 8052 records retrieved, 275 records were considered eligible for full-text screening. Nineteen studies met the inclusion criteria. Data extraction and quality assessment was performed by two independent reviewers. Six of the nineteen included studies were judged to have low risk of bias, and the rest had medium risk of bias. Compounds and particles such as zinc, tin, Selenium, chitosan, chlorhexidine, fluoride and methyl methacrylate were found to be effective in reducing the colony-forming unit counts, producing inhibition zones, reducing the optical density, reducing the metabolic activities, reducing the lactic acid and polysaccharide production and neutralizing the pH when they are added to the resin-based dental sealants. In addition, some studies showed that the antibacterial effect was not significantly different after 2 weeks, 2 months and 6 months aging in distilled water or phosphate-buffered saline. In conclusion, studies have confirmed the effectiveness of adding antibacterial agents/compounds to dental sealants. However, we should consider that these results are based on laboratory studies with a high degree of heterogeneity.

Antibacterial Additives in Epoxy Resin-Based Root Canal Sealers: A Focused Review

Dental materials used in root canal treatment have undergone substantial improvements over the past decade. However, one area that still remains to be addressed is the ability of root canal fillings to effectively entomb, kill bacteria, and prevent the formation of a biofilm, all of which will prevent reinfection of the root canal system. Thus far, no published review has analysed the literature on antimicrobial additives to root canal sealers and their influence on physicochemical properties. The aim of this paper was to systematically review the current literature on antimicrobial additives in root canal sealers, their anti-fouling effects, and influence on physicochemical properties. A systematic search was performed in two databases (PubMed and Scopus) to identify studies that investigated the effect of antimicrobial additives in epoxy resin-based root canal sealers. The nature of additives, their antimicrobial effects, methods of antimicrobial testing are critically discussed. The effects on sealer properties have also been reviewed. A total of 31 research papers were reviewed in this work. A variety of antimicrobial agents have been evaluated as additives to epoxy resin-based sealers, including quaternary ammonium compounds, chlorhexidine, calcium hydroxide, iodoform, natural extracts, antibiotics, antifungal drugs, and antimicrobial agent-functionalised nanoparticles. Antimicrobial additives generally improved the antimicrobial effect of epoxy resin-based sealers mainly without deteriorating the physicochemical properties, which mostly remained in accordance with ISO and ANSI/ADA specifications.

Physicochemical and Biological Evaluation of Endodontic Filling Materials for Primary Teeth

This study assessed the pH, radiopacity, antimicrobial effect, cytotoxicity and biocompatibility of endodontic filling materials for primary teeth. Zinc oxide eugenol (ZOE), Vitapex and Calen paste thickened with zinc oxide (ZO) were evaluated in comparison to an experimental MTA-based material. Radiopacity was tested using a graduated aluminum stepwedge with a digital sensor (n=5). The materials pH was recorded at 1, 4, 12 h; 1, 3, 7, 15 and 30 days (n=5). Direct contact test was used to assess the antimicrobial efficacy against Enterococcus faecalis after 1, 4, 12, 24 h (n=5). Cytotoxicity assay used MTT test for cell viability after incubation for 1, 3 and 7 days (n=5). For biocompatibility test, Wistar rats had received implants containing each material (n=5). The biopsied tissues were histologically analyzed after 15, 30 and 60 days. The results of radiopacity, pH, antimicrobial capacity and cytotoxicity were analyzed using ANOVA and Tukey tests. The histological data were submitted to Kruskal-Wallis test. The experimental material presented the lowest radiopacity (3.28 mm Al) and had a pH>12.0 throughout the test period. The experimental material showed the highest antibacterial effect, killing over 99.97% bacteria in 4 h. Vitapex presented the highest cell viability. Initially, biocompatibility test showed moderate to severe inflammation in all groups. After 60 days, Calen+ZO group showed moderate inflammation, while the others showed predominantly mild inflammatory reaction. The present results demonstrated that the experimental MTA-based material exhibited satisfactory behavior regarding the studied properties. Additional in vivo studies are necessary for a better evaluation of the material.

Importance and methodologies of endodontic microleakage studies: A systematic review

INTRODUCTION

It is very important to obtain a tight seal in obturated root canal, making it necessary to conduct clinical or laboratory studies on the sealability of endodontic materials. Different methodologies have been historically used to assess microleakage of different endodontic materials. The aim of the present study was to comprehensively review different material testing methods used in microleakage studies, their interpretation and importance in endodontic literature.

MATERIAL AND METHODS

A systematic search was conducted in Medline, Cochrane, and Web of Science databases. In addition, the reference lists of review articles on the topic were searched. No language restriction was applied. Two independent reviewers screened the article.

RESULTS

Microleakage is considered the single most important risk factor responsible for apical periodontitis. Dye penetration, dye diffusion, bacterial and endototoxin infiltration, fluid filtration, glucose, caffeine and protein infiltration, radioisotope penetration, animal studies, and electrochemical or 3D evaluation are different methodologies used to assess dental leakage. 91 out of 177 articles in the primary search were included in the study. These methods are very divergent in their viewpoints; that is why their results cannot be easily compared. It is necessary to standardize microleakage detection methods in order to more correctly evaluate the phenomena that are found between the root canal wall and the root canal filling materials.

CONCLUSIONS

All the methods are useful if studies are performed strictly with large sample sizes and proper control groups and if the technique can be standardized. Furthermore, more evaluations of the reliability of the methods are strongly recommended. Key words:Dental leakage, review, root canal, material testing methods, data interpretation.

Capacidade de selamento e penetração intratubular do MTA Fillapex e do AH Plus em dentes humanos

Resumo Introdução O MTA é um importante material de uso na odontologia, com boas propriedades biológicas. As respostas experimentais aos cimentos endodônticos que utilizam este composto no selamento e preenchimento do sistema de canais radiculares, aliados a uma boa instrumentação e limpeza, podem ser importantes no processo de reparo periapical. Objetivo Avaliar in vitro a profundidade de penetração de dois diferentes cimentos endodônticos nos túbulos dentinários e a infiltração bacteriana em obturações com os cimentos AH Plus e MTA Fillapex. Material e método 34 pré-molares monorradiculados humanos foram selecionados, suas coroas removidas e suas raízes padronizadas em 16 mm, a seguir foram, então, divididos aleatoriamente em dois grupos de 15 espécimes e instrumentados com o sistema rotatório Pro Taper. Um grupo foi obturado com o cimento AH Plus (Grupo AH) e outro com MTA Fillapex (Grupo FI). Nestes grupos, avaliaram-se a infiltração coronária de bactérias para Enterococcus Faecalis e a profundidade de penetração nos túbulos dentinários. Para a aferição da infiltração bacteriana, usou-se o teste exato de Fisher; para a penetração intratubular, usou-se o teste-t. Resultado Para a infiltração bacteriana, considerando o número de amostras infiltradas para AH e MTA Fillapex, houve diferença estatística significativa (p=0,0341). Na avaliação da penetração intratubular, a diferença entre os dois grupos de cimentos foi considerada estatisticamente significativa (p=0,0006). Conclusão Ambos os cimentos apresentaram infiltração bacteriana, sendo que o MTA Fillapex teve pior desempenho. A capacidade de penetração nos túbulos dentinários do AH Plus foi significativamente maior que a do MTA Fillapex.

Solubility and bacterial sealing ability of MTA and root-end filling materials

Objective

To evaluate solubility and sealing ability of Mineral Trioxide Aggregate (MTA) and root-end filling materials.

Material and Methods

The materials evaluated were: MTA, Calcium Silicate Cement with zirconium oxide (CSC/ZrO₂), and zinc oxide/eugenol (ZOE). Solubility test was performed according to ANSI/ADA. The difference between initial and final mass of the materials was analyzed after immersion in distilled water for 7 and 30 days. Retrograde cavities in human teeth with single straight root canal were performed by using ultrasonic tip CVD 9.5107-8. The cavities were filled with the evaluated materials to evaluate sealing ability using the bacterial leakage test with Enterococcus faecalis. Bacterial leakage was evaluated every 24 hours for six weeks observing the turbidity of Brain Heart infusion (BHI) medium in contact with root apex. Data were submitted to ANOVA followed by Tukey tests (solubility), and Kruskal-Wallis and Dunn tests (sealing ability) at a 5% significance level.

Results

For the 7-day period, ZOE presented highest solubility when compared with the other groups (p<0.05). For the 30-day period, no difference was observed among the materials. Lower bacterial leakage was observed for MTA and CSC/ZrO₂, and both presented better results than ZOE (p<0.05).

Conclusion

MTA and CSC/ZrO₂ presented better bacterial sealing capacity, which may be related to lower initial solubility observed for these materials in relation to ZOE.

In Vitro Antimicrobial Effectiveness of Root Canal Sealers against Enterococcus faecalis: A Systematic Review

INTRODUCTION

The purpose of this systematic review was to summarize the outcomes of in vitro studies of root canal sealers for their antimicrobial effectiveness against Enterococcus faecalis on the basis of direct contact test.

METHODS

An exhaustive literature search was performed by using MEDLINE, Scopus, TRIP, and OpenThesis databases, followed by an extensive hand search of references of identified articles. Two independent reviewers evaluated the studies for eligibility against inclusion and exclusion criteria and performed data abstraction and risk of bias evaluations.

RESULTS

A total of 31 articles were assessed for eligibility. Of these, 24 met the inclusion criteria and were included in the systematic review. A considerable heterogeneity was found in the methodologies of included studies. Therefore, it was not feasible to perform meta-analysis. Majority of the studies reported that different categories of freshly prepared sealers possessed some form of positive antimicrobial activity against E. faecalis for up to 24 hours. Antimicrobial efficacy was lost as the material set. Moderate evidence was found for no antimicrobial activity of aged (2-day to 7-day set) sealer samples across all categories.

CONCLUSIONS

The evidence indicated positive antimicrobial activity of freshly mixed sealers against E. faecalis. Antimicrobial efficacy was lost as the material set, with no bacterial growth inhibition by 2-day to 7-day set sealer samples. However, the studies included in this review presented medium to high risk of bias. This review identified the need for the development of standardized methods to evaluate antimicrobial activity of root canal sealers in in vitro studies.

Cytotoxicity, genotoxicity and antibacterial effectiveness of a bioceramic endodontic sealer

AIM

To compare the characteristics of bioceramic endodontic sealer Endosequence BC sealer with those of AH Plus sealer.

METHODOLOGY

Cytotoxicity and genotoxicity were analysed on human gingival fibroblasts submitted to cell culture medium conditioned by sealers using the MTT reduction assay and micronucleus formation test (MNT), respectively. Cells grown on fresh medium served as controls. Cell viabilities were measured at 1, 3, 5 and 7 days. The antibacterial activity was analysed on an Enterococcus faecalis strain (ATCC 29212) using both on agar diffusion test (ADT) and a direct contact test (DCT). The inhibition zones in ADT were measured after 48 h and the colony-forming units counting in the DCT after 1, 24, 72 and 168 h. Data were compared by anova and Tukey's test and MNT by Fisher's exact test (P < 0.05).

RESULTS

Cultures submitted to Endosequence BC sealer had a significantly higher number of viable cells (P < 0.01) and less micronucleus formation (P < 0.05) than AH Plus sealer. Endosequence BC sealer exhibited significantly smaller inhibition zones (6.00 ± 0.03 mm) than AH Plus sealer (10.31 ± 0.21 mm) (P < 0.05). Moreover, Endosequence BC sealer had significantly smaller antibacterial activity than AH Plus sealer up to 1 h of direct contact (P < 0.05). On other exposure times, both materials had similar antibacterial effectiveness (P > 0.05).

CONCLUSIONS

Bioceramic-based sealer had less cytotoxicity and genotoxicity and similar antibacterial effect against E. faecalis in comparison with AH Plus sealer.

Quantitative microleakage analysis of root canal filling materials in single-rooted canals

The purpose of this study was to analyze the sealing ability of different root canal filling materials over a 6-week period using a glucose penetration model. Forty-six recently extracted human premolars were used in this study. The root canals were enlarged to 40/0.06. Prepared canals were randomly assigned into four groups (n = 10) as follows: Group 1, Gutta-Percha (GP)/AH Plus with cold lateral compaction; Group 2, GP/AH Plus with continuous wave compaction; Group 3, RealSeal SE obturation system; and Group 4, OrthoMTA. The remaining specimens were used as positive and negative controls, and all specimens underwent thermocycling (10,000; 5-55 °C). The sealing ability of all samples was evaluated at 24 h, 1, 2, 4, and 6 weeks using a quantitative glucose leakage model, and scanning electron microscope (SEM) images were taken. A mixed effect analysis using R statistical language was performed. Groups 1, 2, and 4 showed low leakage levels during experimental periods. Group 3 showed low leakage levels for the first 2 weeks; however, the leakage level was significantly increased after 2 weeks compared to negative control group (p < 0.05). In the SEM results, Group 3 showed imperfect dentin bonding, whereas Group 4 showed calcium silicate hydrate short tags, which are formed at the access of the dentin tubules. GP/AH Plus and OrthoMTA showed less microleakage than RealSeal SE obturation system when used as root canal filling materials. Traditional GP/AH Plus sealer and the newly developed OrthoMTA are more appropriate for ideal sealing of the root canals.

Quantitative microleakage analysis of endodontic temporary filling materials using a glucose penetration model

OBJECTIVE

The purpose of this study was to analyze the sealing ability of different temporary endodontic materials over a 6-week period using a glucose penetration model.

MATERIALS AND METHODS

Standardized holes were formed on 48 dentin discs from human premolars. The thicknesses of the specimens were distributed evenly to 2 mm, 3 mm and 4 mm. Prepared dentin specimens were randomly assigned into six groups (n = 7) and the holes in the dentin specimens were filled with two kinds of temporary filling materials as per the manufacturers' instructions as follows: Caviton (GC Corporation, Tokyo, Japan) 2 mm, 3 mm, 4 mm and IRM (Dentsply International Inc., Milford, DE) 2 mm, 3 mm, 4 mm. The remaining specimens were used as positive and negative controls and all specimens underwent thermocycling (1000; 5-55°C). The sealing ability of all samples was evaluated using the leakage model for glucose. The samples were analyzed by a spectrophotometer in quantitative glucose microleakage test over a period of 6 weeks. As a statistical inference, a mixed effect analysis was applied to analyze serial measurements over time.

RESULTS

The Caviton groups showed less glucose penetration in comparison with the IRM groups. The Caviton 4 mm group demonstrated relatively low glucose leakage over the test period. High glucose leakage was detected throughout the test period in all IRM groups. The glucose leakage level increased after 1 week in the Caviton 2 mm group and after 4 weeks in the Caviton 3 mm and 4 mm groups (p < 0.05).

CONCLUSIONS

Caviton had better sealing ability than IRM in the glucose penetration model during 6 weeks. Temporary filling of Caviton to at least 3 mm in thickness is necessary and temporary filling periods should not exceed 4 weeks.

In Vitro Evaluation of the Antimicrobial Efficacy of Four Endodontic Biomaterials against Enterococcus faecalis, Candida albicans, and Staphylococcus aureus

Root canal sealers that possess good antimicrobial property can prevent residual and recurrent infection and contribute to successful endodontic therapy. This study evaluated the antimicrobial activity of four endodontic sealers, AH Plus, Tubliseal EWT, EndoRez, and iRoot SP, against three different microorganisms, E. faecalis, C. albicans, and S. aureus, by direct contact test. 10 μL microbial suspensions were allowed to directly contact the four endodontic sealers for 1 hr at 37°C. Subsequently microbial growth was measured spectrophotometrically every 30 min for 18 hours. The microbial suspensions were simultaneously tested to determine the antimicrobial effect of components which are capable of diffusing into the medium. The results revealed that AH Plus and iRootSP had significantly higher antimicrobial activity against E. faecalis. AH Plus and Tubliseal EWT showed significantly higher antimicrobial activity against C. albicans and S. aureus compared to iRoot SP and EndoRez. EndoRez showed the least antimicrobial activity against all the three microorganisms. Inhibition of microbial growth is related to the direct contact of microorganisms with the sealers. In conclusion AH Plus had significantly higher antimicrobial activity against E. faecalis, C. albicans, and S. aureus.

Ability of new obturation materials to improve the seal of the root canal system: a review

New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials.

Towards antibacterial endodontic sealers using quaternary ammonium nanoparticles

AIM

To change and characterize the antibacterial properties of endodontic sealers by incorporating low concentrations of insoluble antibacterial nanoparticles (IABN).

METHODOLOGY

The antibacterial effect against Enterococcus faecalis was evaluated by (i) agar diffusion test (ADT), (ii) direct contact test (DCT) and (iii) scanning electron microscopy (SEM). IABN were incorporated into AH Plus (Dentsply, DeTrey Konstanz, Germany) and GuttaFlow (Coltène Whaledent, Langenau, Germany) at concentrations of 0.5%, 1% or 2% weight/weight. Bacterial growth rates were analysed using ANOVA followed by Tukey's test.

RESULTS

The antibacterial tests demonstrated total bacterial growth inhibition using AH Plus samples incorporating 2% weight/weight IABN after 4 weeks (P < 0.005). DCT showed total growth inhibition of up to 6 logs in viable count in AH Plus samples incorporating IABN and up to 4 log in count in GuttaFlow incorporating IABN (P < 0.005). Significant differences were found between the unmodified sealers and the experimental groups. No antibacterial effect was observed in the ADT, indicating IABN were not diffusing into the agar. Furthermore, SEM indicated bacterial cell wall damage and lysis.

CONCLUSIONS

AH Plus and GuttaFlow incorporating low concentrations of IABN exhibited significant and stable antimicrobial properties.

Development of a new quantitative gas permeability method for dental implant-abutment connection tightness assessment

Background

Most dental implant systems are presently made of two pieces: the implant itself and the abutment. The connection tightness between those two pieces is a key point to prevent bacterial proliferation, tissue inflammation and bone loss. The leak has been previously estimated by microbial, color tracer and endotoxin percolation.

Methods

A new nitrogen flow technique was developed for implant-abutment connection leakage measurement, adapted from a recent, sensitive, reproducible and quantitative method used to assess endodontic sealing.

Results

The results show very significant differences between various sealing and screwing conditions. The remaining flow was lower after key screwing compared to hand screwing (p = 0.03) and remained different from the negative test (p = 0.0004). The method reproducibility was very good, with a coefficient of variation of 1.29%.

Conclusions

Therefore, the presented new gas flow method appears to be a simple and robust method to compare different implant systems. It allows successive measures without disconnecting the abutment from the implant and should in particular be used to assess the behavior of the connection before and after mechanical stress.

Is endodontic re-treatment mandatory for every relatively old temporary restoration? A narrative review

OBJECTIVES AND BACKGROUND

In this review, the authors examine whether there is any decisive evidence to support the revision of root fillings that have been exposed to the oral environment for more than three months, undertaken solely because of suspicions of microleakage. Researchers in numerous endodontic studies have addressed the evaluation of coronal microleakage by using different tracers and techniques. The need to achieve a tight, permanent coronal seal as soon as possible after the completion of endodontic treatment is obvious. However, the clinical importance of microleakage studies recently has been questioned because of their wide range and even contradictory results, and findings from only a few clinical investigations have demonstrated a clear relationship between the endodontic success rate and failure rate owed to coronal microleakage in cases involving high-quality endodontic therapy.

METHODS

The authors analyzed commonly cited articles regarding the clinical relevance of microleakage studies and the success rate of teeth with compromised restorations.

CONCLUSIONS

In a review of the literature, the authors found no clear evidence to support immediate replacement of well-obturated endodontic treatment that has lasted more than three months solely because of suspicions of microleakage. It may be prudent in such cases to make a new coronal restoration immediately and to observe the tooth for at least three months before placing the permanent crown.

Potential systematic error in laboratory experiments on microbial leakage through filled root canals: review of published articles

AIM

To systematically evaluate whether published studies on microbial leakage through filled root canals in human teeth embedded in a two-chamber system were properly controlled. Specifically, the control for the assumption that leakage should occur through the root canal rather than other routes was investigated.

METHODOLOGY

A systematic search was conducted using Medline, Biosis, Cochrane, Embase, and Web of Science databases. In addition, the reference lists of review articles pertaining to the topic were searched. No language restriction was applied. Two independent reviewers screened titles and abstracts. All articles deemed appropriate by either reviewer were included in the full-text evaluation. In case of disagreement, a referee arbitrated between the reviewers.

RESULTS

With 93.8% agreement prior to discussion and arbitration, 67 articles were included. On average, the size of the negative control group was 30% (mean) of the n in the experimental groups (minimum=0.0%, maximum=100%, SD=27%). The majority of studies (57 of 67) used inadequate negative controls. The whole root was covered with the sealing material in these specimens, whilst the root tip was left uncovered in the experimental groups. Consequently, leakage between outer root surface and sealing material was not controlled for. The authors of the remaining 10 communications did not state clearly how negative control assessments were performed.

CONCLUSIONS

Experimental investigations should be performed to assess the routes of microbial leakage in two-chamber models.

The quality of single cone and laterally compacted gutta-percha fillings in small and curved root canals as evidenced by bidirectional radiographs and fluid transport measurements

OBJECTIVE

The aim of this study was to examine the quality of root fillings in small and curved root canals using bidirectional radiographs and fluid transport (FT) measurements.

STUDY DESIGN

Root canals in eighty 38 degrees -curved mesial roots of mandibular molars were prepared using a balanced force technique. Samples were divided into 4 groups of 20 each and obturated by either the cold lateral compaction (LC) or the single cone (SC) technique, using either epoxy resin-based or zinc oxide-eugenol sealers. Bidirectional (buccolingual and mesiodistal) radiographs were acquired from each root. The voids along the root filling were assessed. The FT along the root filling was measured using an FT monitoring device. The differences between the groups regarding FT and the bidirectional radiographic score were analyzed by means of a Kruskal-Wallis test. The correlation between the FT values and the radiographic scores were analyzed using a Spearman test.

RESULTS

Three groups of LC or SC fillings containing epoxy resin-based sealers exhibited similar radiographic scores and FT values (P > .05). The group of SC fillings that contained zinc oxide-eugenol sealer had worse radiographic scores than the other groups (P = .047). The bidirectional radiographic scores and the FT values for the 80 filled roots were strongly correlated (r(2) = 0.519; P = .00001).

CONCLUSION

Root fillings of similar quality were confirmed in small and curved root canals filled using either a single cone or laterally compacted gutta-percha and epoxy resin-based sealers.

Antibacterial activity of endodontic sealers by modified direct contact test against Enterococcus faecalis

INTRODUCTION

The antibacterial effectiveness of 7 different endodontic sealers, AH Plus, Apexit Plus, iRoot SP, Tubli Seal, Sealapex, Epiphany SE, and EndoRez against Enterococcus faecalis was studied in vitro.

METHODS

A modified direct contact test was used. Bacteria in suspension were exposed to the materials for 2-60 minutes by using sealers that were freshly mixed or set for 1, 3, and 7 days. The pH values and contact angles of sterile water on sealers at different times after setting were also measured.

RESULTS

Fresh iRoot SP killed all bacteria in 2 minutes, AH Plus in 5 minutes, EndoRez in 20 minutes, and Sealapex and Epiphany in 60 minutes. Freshly mixed Apexit Plus and Tubli Seal failed to kill all bacteria at 60 minutes. For 1-day and 3-day samples, iRoot SP and EndoRez had the strongest antibacterial activity, followed by Sealapex and Epiphany; Tubli Seal and AH Plus did n'ot show any significant antibacterial activity. Of all the samples, Apexit Plus had the lowest antimicrobial activity. The pH of the sealers could not alone explain their antibacterial effect.

CONCLUSIONS

Fresh iRoot SP, AH Plus, and EndoRez killed E. faecalis effectively. IRoot SP and EndoRez continued to be effective for 3 and 7 days after mixing. Sealapex and EndoRez were the only ones with antimicrobial activity even at 7 days after mixing.

Assessment of different dyes used in leakage studies

The goal of this in vitro study was to identify the most suitable dye for endodontic dye leakage studies, which could be a further step towards standardisation. The root canals of 70 extracted, single-rooted human adult teeth were enlarged to apical size 50 using hand instruments. The teeth were divided into seven groups (n = 10 each), and all root canals were completely filled by injection with one of the following dyes: methylene blue 0.5% and 5%, blue ink, black ink, eosin 5%, basic fuchsin 0.5% and drawing ink. Transverse root sections from the coronal, middle and apical part of the roots were examined, and the percentage of the dentine penetrated by dye was evaluated by software-supported light microscopy. In addition, the range of particle size of drawing ink particles was evaluated. There were conspicuous differences in the relative dye penetration into the root dentine and the penetration behaviour in the different root sections (two-way ANOVA, both p < 0.0001). One dye (drawing ink) penetrated less into the root dentine compared with all the others (p <0.0001). The particle size of this agent (0.1-2 microm) corresponds best with the size range of a representative selection of 21 species of pathogenic endodontic bacteria. Compared to the other dyes tested, drawing ink appears to be superior for use in endodontic dye leakage studies. The penetration behaviour into the root dentine of all the other dyes tested might be one factor that limits the applicability of these dyes in dye leakage studies.

Mineral trioxide aggregate in paediatric dentistry

OBJECTIVE

The aim of this study was to present a review of the reported literature on: (i) the physical and chemical properties; and (ii) clinical applications of mineral trioxide aggregate (MTA) in the practice of paediatric dentistry.

METHOD

Electronic literature search of scientific papers from January 1993 to June 2008 was carried out on the MEDLINE, Embase, Entrez Pubmed, and Scopus databases using specific key words. The search yielded 448 papers, out of which 100 were identified as conforming to the applied criteria. These papers formed the basis of the review and the clinical scenarios presented which demonstrate the application of MTA in the practice of paediatric dentistry.

CONCLUSION

Paediatric dentists have successfully employed MTA in a variety of endodontic/restorative applications since the late 1990s. Clinical impressions have generally been favourable and support the findings of laboratory and animal-based investigations. Very few clinical studies have been reported so far in humans, and although these have been positive, the body of research is currently insufficient to enable a meaningful systematic review and meta-analysis.

Glucose reactivity with filling materials as a limitation for using the glucose leakage model

AIM

To evaluate the reactivity of different endodontic materials and sealers with glucose and to asses the reliability of the glucose leakage model in measuring penetration of glucose through these materials.

METHODOLOGY

Ten uniform discs (radius 5 mm, thickness 2 mm) were made of each of the following materials: Portland cement, MTA (grey and white), sealer 26, calcium sulphate, calcium hydroxide [Ca(OH)(2)], AH26,Epiphany, Resilon, gutta-percha and dentine. After storing the discs for 1 week at 37 degrees C and humid conditions, they were immersed in 0.2 mg mL(-1) glucose solution in a test tube. The concentration of glucose was evaluated using an enzymatic reaction after 1 week. Statistical analysis was performed with the anova and Dunnett tests at a significant level of P < 0.05.

RESULTS

Portland cement, MTA, Ca(OH)(2) and sealer 26 reduced the concentration in the test tube of glucose significantly after 1 week (P < 0.05). Calcium sulphate reduced the concentration of glucose, but the difference in concentrations was not significant (P = 0.054).

CONCLUSIONS

Portland cement, MTA, Ca(OH)(2) and sealer 26 react with a 0.2 mg mL(-1) glucose solution. Therefore, these materials should not be evaluated for sealing ability with the glucose leakage model.